Polymer and a flow control agent powdered coating composition of unsaturated glycidyl and anhydride co

ABSTRACT

Powder coating compositions are disclosed. In general, individual powder coating compositions of this invention are a mixture of several materials. The most significant materials employed in the powder coatings include the following. A copolymer containing epoxy and anhydride crosslinkale, functional groups, forms the most important constituent of the powder coating. This copolymer has a glass transition temperature in the range of 40*C to 90*C and a molecular weight (Mn) in the range from about 3,000 to about 10,000. Another material of an individual composition is a flow control agent which forms at least 0.05 percent by weight of the mixture. The flow control agent is a polymer having a molecular weight (Mn) of at least 1000. Also, the flow control agent has a glass transition temperature at least 50*C lower than the glass transition temperature of the copolymer. Other materials which may be employed in individual powder coating compositions are catalysts, pigments, antistatic agents and plasticizers.

iinited States Patent 11 1 Labana et al.

[ POWDERED COATING COMPOSITION OF UNSATURATED GLYCIDYL AND ANHYDRIDECOPOLYMER AND A FLOW CONTROL AGENT [75] Inventors: Santokh S. Labana,Dearborn Heights; Ares N. Theodore, Farmington, both of Mich.

[731 Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Aug. 16, 1971 [21] App]. No.: 172,235

[52] U.S. Cl. 260/836, 117/93.4 R, 117/126 GE, 1 17/126 GR, 117/132 BE,260/30.6 R,

260/31.8 E, 260/31.8 M, 260/37 EP, 260/41 A, 260/41 B, 260/41IC',260/830 R, 260/835 1451 Sept. 11, 1973 3,652,476 3/1972 Fellers 260/830TW Primary ExaminerPaul Lieberman Attorney-Keith L. Zerschling andWilliam E.

Johnson 5 7] ABSTRACT Powder coating compositions are disclosed. Ingeneral, individual powder coating compositions of this invention are amixture of several materials. The most significant materials employed inthe powder coatings include the following. A copolymer containing epoxyand anhydride crosslinkale, functional groups, forms the most importantconstituent of the powder coating. This copolymer has a glass transitiontemperature in the range of 40C to 90C and a molecular weight (M,,) inthe range from about 3,000 to about 10,000. Another material of anindividual composition is a flow control agent which forms at least 0.05percent by weight of the mixture. The flow control agentis a polymerhaving a molecular weight (M,,) of at least 1000. Also, the flow controlagent has a glass transition temperature at least 50C lower than theglass transition temperature of the copolymer. Other materials which maybe employed in individual powder coating compositions are catalysts,pigments, antistatic agents and plasticizers.

5 Claims, No Drawings POWDERED COATING COMPOSITION OF UNSATURATEDGLYCIDYL AND ANHYDRIDE COPOLYMER AND A FLOW CONTROL AGENT BACKGROUND OFTHE INVENTION Powder coating compositions for use in the'painting ofsurfaces are extremely desirable. Such coating compositions aredesirable because they eliminate the solvents utilized in liquid paintsystems, as for example, the paint system shown in U.S. Pat. No.2,857,354 issued Oct. 21, 1958.,A powder coating paint composition iscurable by heat in a manner that little, if any, volatile material isgiven off to the environment. This, of course, is substantiallydifferent from a liquid paint system as the liquid paint vehicle must bevolatilized during the drying of the paint. Volatilization of the liquidvehicle carries such vaporized material into the ambient.

This invention is directed to powder coating compositions which aresuitable for finishing surfaces of articles with a protective anddecorative coating. The coating produced by the compositions of thisinvention are comparable on all terms with the coating produced bypriorart liquid paint systems.

SUMMARY OFTHE INVENTION This invention is directed to powder coatingcompositions and, more particularly, to powder coating compositionswhich are curable by heat and which do not contain external crosslinkingagents. Individual ones of the powder coating compositions formed inaccordance with the teachings of this invention comprise an intimatemixture of several materials. Materials such as antistatic agents,catalysts, plasticizers and pigments may be included in individualcompositions to achieve desired effects. Another material, which is ofsignificant importance, and which is included'in each individual powdercoating composition is a copolymer containing epoxy and anhydridecrosslinkable, functional groups. This copolymer has a glass transitiontemperature in the range of 40C to 90C and a molecular weight (M,,) inthe range from about 3,000 toabout 10,000. In greaterdetail, thecopolymer may contain, for example, (a) approximately stoichiometricquantities of functional, ethylenically unsaturated monomers,

' one containing epoxy functional groups and the other anhydridefunctional groups, and (b) ethylenically unsaturated monomers containingno functional groups and so selected that when both types ofthe-monomers are reacted toproduce the copolymer, the copolymer willhave the glass transition temperature and' molecular weight mentioned. v

Another significant material employed in individual powder coatingcompositions of this invention is a flow control agent which forms atleast 0.50 percent by weight of the total mixture. The flow controlagent is a polymer having a molecular weight'(M,,) of at least 1000. Theflow control agent has-a glass transition temperature at least 50C belowthe glass transition temperature of the copolymer. I

As previously mentioned, a powder coating-composition formed inaccordance with the teachings of this invention may include a smallweight percentage of a catalyst. Generally, the catalyst-is selected toproduce 'a gel time for the powder coating composition greater than oneminute at the bakingtemperature of the composition. The coatingcomposition may also use therein a pigment which can form from about 6percent by weight to about 35 percent by weight of the total mixturedepending on the pigment selected. The powder coating composition mayalso include a small weight percentage of an antistatic agent so thatthe composition may be applied in an electrostatic spray operation.

Some particular materials which have been found suitable for use inmaking powder coating compositions in accordance with the teachings ofthis invention are set forth below. The materials are representative ofthe various types of material which may be used but individual powdercoating compositions of this invention are not limited to these specificmaterials.

The copolymer of the coating composition should contain from about 2percent by weight to about 12 percent by weight of the monomer supplyingthe epoxy functional groups to the copolymer. The monomer sup plying theanhydride functional groups should be present in the copolymer in therange from about 2 percent by'weight to about 8 percent by weight.Glycidyl methacrylate and glycidyl acrylate are monomers which aresuitable for supplying the epoxy functional groups. The anhydridefunctional groups may be supplied by monoiners such as maleic anhydride,itaconic anhydride, citraconic anhydride, dodecenyl succinic anhydride,dichloromaleic anhydride and tetrahydrophthalic anhydride. The monomerscontaining the functional groups are mixed with other, non-functionalgroup containing monomers in order to form a copolymer having thedesired glass transition temperature range and molecular weight range.Some monomers which are suitable for mixing with the functional monomersare methyl methacrylate, butyl methacrylate, ethyl acrylate, butylacrylate, 2-ethylhexyl acrylate, styrene, alpha methyl styrene,acrylonitrile, methacrylonitrile, etc.

With respect'to the flow control agents used in the powder coatingmixture, an individual agent selected for a mixture may be an acrylicpolymer having a glass transition temperature atleast 50C below theglass transition temperature-of the mixture s copolymer. Preferredacrylic polymers which may be used as the flow control agent arepolylauryl acrylate polybutyl acrylate, poly (Z-ethylhexyl acrylate),polylauryl methacrylate, polybutyl methacrylate, poly (Z-ethylhexylmethacrylate) and polyisodecyl methacrylate..

The flow control agent may also be a fluorinated polymer having a glasstransition temperature at least 50Cbelow the glass transitiontemperature of the copolymer utilized in the mixture. Preferred flowcontrol agents, if the agent is a fluorinated polymer, are esters ofpolyethyleneglycol or polypropylerieglycol and fluorinated fatty acids.For example, an ester of polyea gel time of at least 1 minute but nogreater than I0 I minutes. In general, the catalyst is presented in therangeof from 0.05 percent by weight to 1 percent by weight of the weightof the mixture. The most desirable g'eltime produced by the catalyst isin a time range of from about 2 minutes to about 6 minutes. Thesecatalyst gel times are at baking temperatures for the powder coatingcompositions in the range of l30C to 200C.

The powder coating compositions of this invention may also contain fromabout 6 percent by weight to about 35 percent by weight of a pigment.The various pigments already known in the art may be employed in thepowder coating compositions. The pigments are generally selected forcolor, appearance and/or corrosion protection properties.

A small weight percent of an antistatic agent may also be employed inthe powder coating composition. For example, 0.01 percent by weight to0.3 percent by weight of the powder coating composition may be anantistatic agent so that the coating may be applied in an electrostaticspraying operation.

The powder coating compositions of this invention may also contain aplasticizer. If used, the plasticizer is present from about 2 percent byweight to about 10 percent by weight of the powder.

DESCRIPTION OF THE PREFERRED EMBODIMENT A general discussion of thevarious materials which may be employed in the powder coatingcompositions of this invention will be set forth below. Also, aplurality of examples will be employed to show the manner in whichvarious, individual, powder coating compositions, which fall within thescope of this invention are prepared and utilized.

The principal material in individual powder coating compositions is thecopolymer containing epoxy and anhydride crosslinkable, functionalgroups. The copolymer is so formed that it has a glass transitiontemperature in the range of 40C to 90C and a molecular weight (M in therange from about 3,000 to about 10,000. The copolymer is generallyformed from (a) functional monomers containing epoxy functional groupsand anhydride functional groups and (b) modifying monomers containing nofunctional groups (after copolymerization) and so selected that thecopolymer has the glass transition temperature and the molecular weightdescribed. Particular powder coating compositions are made from acopolymer which is formed by reacting (a) approximately stoichiometricquantities of two ethylenically unsaturated monomers, one containingepoxyfunctional groups and the othercontaining anhydride functionalgroups with (b) ethylenically unsaturated monomers containing nofunctional groups.

Glycidyl methacrylate and glycidyl acrylate are particularly desirablemonomers for forming the epoxy supplying monomer for the copolymer. Whenthese materials are used, they are present in the copolymer from about 2percent by weight to about 12' percent by weight. i

Maleic anhydride, itaconic anhydride, citraconic anhydride, duodecenylsuccinic anhydride, dichloromaleic anhydride, and tetrahydrophthalicanhydride are particularly desirable monomers for'forming the anhydridesupplying monomer for the copolymer. When these materials are used, theyare present in the copolymer from about 2 percent by weight to about 8percent by weight.

The nonfunctional monomers which may be reacted with the functionalmonomers to produce the copolymer having the stated glass transitiontemperature and molecular weight are many in number. Some of thepreferred nonfunctional monomers are methyl methacrylate, butylmethacrylate, ethyl acrylate, butyl acrylate, Z-ethylhexyl acrylate,styrene, alpha methyl styrene,- acrylonitrile and methacrylonitrile.

The copolymers can be prepared by a variety of methods. Generally, afree radical initiator is needed to induce polymerization reaction. Alarge number of free radical initiators are known in the art. Theseinclude benzoyl peroxide, lauryl peroxide, t-butylhydroxyperoxide,acetylcyclohexane sulfonyl peroxide, diisobutyrl peroxide,di-(Z-ethylhexyl) peroxydicarbonate, diisopropyl peroxydicarbonate,tbutylperoxypivalate, decanoyl peroxide, azobis (2- methylpropionitrile)known as AIBN, etc. The polymerization is preferably carried out insolution using a solvent in which the copolymer is soluble. Toluene,benzene, xylene, dioxane, butanone, etc., are suitable solvents forpolymerization. If the copolymer is prepared in solution it can be usedin that form or the solid copolymer can be obtained by evaporating thesolvent under vacuum or spray drying techniques. Alternatively, thecopolymer can be precipitated by pouring the copolymer solution at aslow rate into a non-solvent liquid such as hexane, octane or waterunder a suitable agitation condition. The copolymer thus obtained canthen be dried so that it contains less than 3 percent of the volatileliquids.

The copolymers can also be prepared by emulsion polymerization,suspension polymerization,- bulk polymerization or their suitablecombination. In these methods of preparing the copolymers, chaintransfer agents may be required to control the molecular weight of thecopolymer to a desired range.

For powder coating applications, molecular weight and molecular weightdistribution of the copolymer is important. Copolymer of averagemolecular weight (1],) in the range of 3,000to 10,000 are suitable.These copolymers, however, must not contain significant amounts ofhigher molecular weight fractions. No more than 2 percent of thecopolymer can be of molecular weight greater than 20,000. The molecularweight distribution as measured by the ratio of weight average molecularweight to number average molecular weight (M /M should be in the rangeof 1.6 to 2.1 The pre-' ferred range of molecular weight distributionisin the range of 1.7 to 1.8.

Aflow control agent is also included in forming each individual one ofthe powdercoating compositionsof this invention. The flow control agentforms at least 0.05 percent by weight of an individual powder coat-.

ing. The flow control agent generally. does not exceed about 4 percentby weight of any individual powder coating composition. In general, theflow control agent is a polymer havinga molecular weight on. of at least1000. Further, the flow control agent has a glass transition temperatureat least 50C below the glass transition temperature of the copolymeremployed in forming the composition.

One type of material which is used as a flowcontrol I agent in thepowder coating compositions is an acrylic polymer having a glasstransition temperature at least 50C below the glass transitiontemperature of the composition's copolymer. Some acrylic polymers whichare preferred as flow control agents are polylauryl acrylate, polylaurylmethacrylate, polybutyl acrylate, polybutyl methacrylate, poly(Z-ethylhexyl acry-.

late) and poly (Z-ethylhexyl methacrylate). Acrylic polymers to be usedas flow control agents can be prepared by polymerization of the acrylateor methacrylate monomers in bulk or in suitable solvent using well knownfree radical initiators. The amount of the initiator and thepolymerization conditions are chosen so that polymer formed hasmolecular weight (Ki above 1000. The preferred molecular weight range ofthe acrylate polymer is above 5000. The most preferred range of theacrylate polymer is 6,000 to 20,000.

Although polymeric acrylate flow control agents are preferred,fluorinated polymers have been found to act as flow control agents forthe powder coating compositions. Such fluorinated polymers are esters ofpolyethyleneglycol or polypropylene glycol and fluorinated fatty acids.Esters of polyethylene glycol of molecular weight (M of over 2,500 andperfluoro octanoic acid are useful as flow control agents for thecompositions of this invention.

The compositions of this invention can each contain a small, effectiveweight percentage of a catalyst. in

general, the catalyst is present in an individual compo I sition in arange from 0.05 percent by weight to 1.0 percent by weight. The catalystis selected to produce a gel time for the powdercoating compositiongreater than at least 1 minute at the baking temperature of thecomposition. A suitable catalyst is also one which will produce a geltime that does not exceed 40 minutes. As used herein, the gel time of acoating composition is that time in which the coating compositiondevelops elasticity and resistance to flow at the baking tempera ture.

Some catalysts which are suitable for use in the powder coatingcomposition include tetralkylammonium salts, imidazole type catalysts,tertiary amines, triaryl phosphates and metal salts or organiccarboxylic acids. The tetralkylammonium salts catalysts include thefollowing: tetrabutylammonium chloride (bromide or iodide),tetraethylammonium chloride (bromide oriodide), 'tetramethylammoniumchloride, dodecyl dimethyl (2-phenoxyethyl) ammonium bromide and diethyl(Z-hydroxy ethyl) methyl ammonium bromide. Suitable catalysts of theimidazole type include: 2- methyl- 4-ethyl imidazole, Z-methylimidazole, imidazole, 2- [(N-benzylanilino) methyl] -2-imidazolinephosphate, and 2-benzyl-2-imidazoline hydrochloride. Suitable tertiaryamine catalyst for the powder coating compositions of this inventioninclude: trithylenediamine, N,N-diethylcyclohexylamine, and N-methylmorpholine. The metal'salts of organic carboxylic acid which arecatalyst for the powder coatings of this invention include, but are notlimited to: stannous octoate, zinc naphthenate, cobalt naphthenate, zincoctoate, stannous 2-ethylhexoate, phenylmercuric propionate, leadneodecanoate, dibutyl tin dilaurate and lithium benzoate. An example oftriarylphosphate type catalyst is triphenylphosphate.

The catalyst used in an individual powder coating composition ispreferably solid at room temperature and has a melting point of from 50Cto200C. As previously specified, the catalyst is present in a powdercoating composition from 0.05 percent by weight to 1.0 percent by weightof the total weight of the powder composition. Further, the catalystproduces a gel time of at least 1 minute and no greater than 40 minutes.Generally, the preferred gel time of the composition is in the range offrom 1 minute to approximately 6 minutes at the baking temperature ofthe composition.

sebacate.

Having generally Since individual powder coating compositions of thisinvention can be applied to an article to be painted by electrostaticmethods, it is preferred to include a small weight percentage of anantistatic agent in such compositions so that the deposition thereof isaccomplished in a proper manner. In particular, the antistatic agent isincluded in a range from 0.01 percent to 0.3 percent by weight of thetotal powder composition. Suitable antistatic agents include, but arenot limited to, tetralkylammonium salts as discussed previously andwhich also serve as catalyst. Other suitable antistatic agents include:alkyl-poly (ethyleneoxy) phosphates as, for example, dibu'tylpoly(ethyleneoxy) phosphate or alkylaryl poly (ethyleneoxy) phosphates asfor example, ethyl benzyl poly (ethyleneoxy) phosphate, pyridinehydrochloride or inorganic salts such as lithium perchlorate.

In order to give individual powder coating compositions of thisinvention a suitable color, a pigment is included in the coatingcomposition. in general, the pigment forms from about 6 percent byweight to about 35 percent by weight of the total powder coatingcomposition. Pigments which are suitable for powder coating compositionsinclude, but are not limited to,'the following: basic lead silicochromate 30 percent by weight (orange); titanium dioxide 30 percent byweight (white); titanium dioxide l5 percent by weight plus ultra marineblue 10 percent by weight (blue); phthalocyanine blue 7 percent byweight plus titanium dioxide 10 percent by weight-(blue); phthalocyaninegreen 7 percent by weight plustitanium dioxide l0 percent by weight(green); ferrite yellow 7 percent by weight plus titanium dioxide 10percent by weight (yellow); carbon black pigment 6 percent by weight(black); black iron oxide 10 percent by weight (black); chromium greenoxide 8 percent by weight plus titanium dioxide 10 percent by weight(green); quindo red 5 percent by weight plus titanium dioxide 16 percentby weight (red); and iron oxide transparent orange pigment 10 percent byweight (orange).

A plasticizer may be used in a powder coating composition of thisinvention if desired. The type of plasticizers used very often includeadipates, phosphates, phthalates, sebacates, polyesters derived fromadipic acid or azelaic acid, and epoxy or epoxidized plasticizers. Someof these plasticizers are; adipates: di(nhexyl) adipate, diisooctyladipate, dicyclohexyl adipate; phosphates: triphenylphosphate,tricreylphosphate, tributylphosphate; phthalates: dibutylphthalate,dioctyphthalate, butyl octyl phthalate;and sebacates: dioctyl sebacate,butyl benzyl sebacate, and dibenzyl described the various materialswhich are employed in formulating the powder coating composition of thisinvention, a plurality'of examples will bev set forth to illustratevarious individual powder I coating compositions.

EXAMPLE 1 The monomers ,.maleic anhydride 4 grams, styrene 4 grams,glycidyl methacrylate 6 grams, methyl methacrylate 46 grams, butylmethacrylate 40 grams, and the initiator t-butylperoxypivate 3 grams isformed into a mixture. Three hundred grams of benzene is charged into a1 liter flask which is equipped with a dropping funnel, condenser,stirrer, thermometer and nitrogen A inlet. The monomer mixture is placedin the dropping funnel. The flask is heated to 80C and a refluxing ofthe solvent is achieved. While maintaining the reaction temperature at80C, the monomer mixture is added in a dropwise fashion over a 2 hourperiod. After the addition is complete, the reaction is continued foranother two hours. The contents of the flask is then cooled to roomtemperature.

One hundred ml of the monomer solution is mixed with: titanium dioxide4.6 grams, ferrite yellow 5.7 grams, poly (2-ethylhexyl acrylate)(lV1,,)=9000, 0.3 grams. The mixture is dispersed and then is dried in avacuum oven at 70C. The powder coating obtained is ground to passthrough a 200 mesh sieve.

The resulting powder thus obtained is a powder coating composition ofthe invention. The powder is sprayed onto an electrically grounded,steel panel by using electrostatic powder spray gun operating at 50 KVcharging voltage. After spraying, the panel is heated at 175C. for 20minutes.

The coating obtained on the panel has good adhesion to the steel paneland good impact strength. The coating also is applied to and has goodadhesion on panels of glass, brass, zinc, aluminum, copper and bronze.The coating obtained is not soluble in toluene, gasoline, butanone ormethanol.

EXAMPLE 2 The monomers, maleic anhydride 3 grams, glycidyl methacrylate8 grams, styrene 4 grams, methyl methacrylate 40 grams, butyl acrylate45 grams, and the initiator 2,2'-azobis (Z-methyl-propionitrile) (AIBN)are formed into a mixture. The mixture is reacted in accordance with theprocedure of Example 1. The cooled, reacted mixture, however, is spraydried at 60C air temperature. The spray dried powder is ground to passthrough a 100 mesh screen.

One hundred parts by weight of the ground copolymer are mixed with thefollowing materials:

Tetrabutyl ammonium bromide 0.1 parts Polylauryl acrylate ($1,310,000)0.5 parts Titanium dioxide 30 parts The materials are mixed together ina ball mill for 2 hours. The mixture is milled rolled at 85C to 90C for5 minutes. The solid obtained is ground in a ball mill to pass through a140 mesh screen.

The resulting powder thus obtained in a powder coating composition ofthe invention. The powder is sprayed on an electrically grounded, steelpanel by using electrostatic powder spray gun operating at 50 KVcharging voltage. After spraying, the panel is heated at 175C for 20minutes.

The coating obtained on the panel has good adhesion to the steel paneland good impact strength. The coating also is applied to and has goodadhesion on panels of glass, brass, zinc, aluminum, copper and bronze.The

coating obtained is not soluble in toluene, gasoline, butanone ormethanol.

EXAMPLE 3 mixed with the same additional ingredients described inExample 2.

The powder coating composition obtained by follow ing the process stepsset forth in Example 2 is applied to test panels in the same manner asdescribed in Example 2. The coating is baked at a temperature of 170Cfor 30 minutes. The coating obtained has good adhe sion to steel, glass,brass, zinc, aluminum, copper and bronze.

EXAMPLE 4 The monomers, maleic anhydride 4.5 grams, glycidylmethacrylate 4.5 grams, methyl methacrylate 50 grams, butyl methacrylate41 grams, and the initiator AIBN 3 grams are reacted and processed asdescribed in Example 2 to produce a ground copolymer.

The ground copolymer parts by weight) is added to the followingmaterials:

Tetrabutyl ammoniu rn chloride 0.1 parts Polybutylacrylate (M,,=9000) 4parts Titanium dioxide 15 parts Epon l00l 10 parts Ultra marine blue 10parts The above ingredients are mixed together and processed inaccordance with the procedure of Example 2 to obtain a powder coatingcomposition. The powder coating composition is sprayed on various testpanels of steel, glass, brass, zinc, aluminum, copper and bronze. Thecoating obtained on each test panel after curing of the powder coatingcomposition at a temperature of 200C for 10 minutes is of good quality,and is solvent and scratch resistant.

EXAMPLE 5 The monomers, maleic anhydride 4 grams, glycidyl methacrylate8 grams, styrene 18 grams, methyl methacrylate 65 grams, ethyl acrylate5 grams, and the initiator AIBN 1 gram are reacted in accordance withthe procedure of Example 1. The cooled, reacted mixture,

however, is vacuum dried at 60C. The dried powder is then ground to passthrough a 100 mesh screen.

One hundred parts by weight of the copolymer obtained is mixed with thefollowing materials:

2-meth l- 4-ethfllimidazole 0.05 parts Dibuty poly(et yleneoxy)phosphate 0.05 parts Polyisododecylmethacrylate 4 parts Titanium dioxide10 parts Phtlhalocyanine blue 7 parts A powder coating composition isobtained by following the process steps set forth in Example 2. Thecoating composition is applied to a series of test panels and baked atthe temperature of and for the same time as Example 4. The coatingobtained on the various test panels is of good quality with respect toits adhesion appearance and impact characteristics.

EXAMPLE 6 A monomer mixture having the following composition isprepared: itaconic anhydride 4 grams, glycidyl methacrylate 5 grams,methyl methacrylate 46 grams, butyl methacrylate 45 grams, and theinitiator AIBN 4 grams. This mixture is reacted and processed asdescribed in Example 5 to produce a ground copolymer.

One hundred parts by weight of the copolymer obtained is added to thefollowing materials:

Trielhylene diamine 0.05 parts Tetraethylammonium chloride 0 05 partsPolylaurylmethacrylate.(M.==6000) 2 parts 7 parts Phthaloycanine green10 parts minutes.

The coating obtained has good adhesion to steel,

. glass, brass, zinc, aluminum, copper and bronze and is insoluble intoluene, gasoline, methanol and butanone.

EXAMPLE 7 A monomer mixture having the followingcomposition is prepared:itaconic anhydride grams, glycidyl methacrylate 5 grams, methylmethacrylate 70 grams, ethyl acrylate 20 grams, and the initiator AIBN 3grams. The mixture is reacted and processed as described in Example 5 toproduce a ground copolymer.

One hundred parts by weight of the copolymer obtained is added to thefollowing materials:

1 part 2 parts 6 parts 7 parts parts Tetramethyl ammonium chlofldePoly(2-ethylhexyl acrylate) (M.==20,000) Epon [002 Ferrite yellowTitanium dioxide This mixture is processed as described in Example 2 inorder to form a powder coating composition. The powder coatingcomposition is applied to test panels as described in Example 2. Thepanels are baked at a temperature of 180C for 5 minutes. The adhesionquality of the powder coating after baking on the various test panels isgood. The coating on each panel possesses good solvent and scratchresistance.

. EXAMPLE 8 Trimethyl benzyl ammonium chloride Poly(2-ethylhexylacrylate) (Mp1 1,000) Epon 1002 Carbon black 2 parts 8 parts 6 parts Theabove materials are mixed and proce'ssed'as set forth in Example 2. Theresulting powder coating composition is applied totestpanelsas'specified in 'Exampie 2. The coatingcomposition is baked at170C for minutes. All the painted panels exhibit good adhesion andsolvent resistance properties.

EXAMPLE 9 A monomer mixture having the following composition isprepared: itaconic anhydride 5 grams, glycidyl methacrylate 7 grams,methyl methacrylate 33 grams, butyl methacrylate 55 grams, and .theinitiator AIBN 3 grams. The mixture is reacted and processed asdescribed in Example 2 to produce a ground copolymer.

One hundred parts of the ground copolymer obtained is added to thefollowing materials:

Dodecyldimethyl (Z-phenoxy-ethyl) 0.5 parts 0.1 part ammonium bromidePolyethylenemglycol rfluro 2 parts octonoate .=34

Black iron oxide 10 parts Butyl benzyl phthalate 3 parts The mixture soformed is processed as described in Example 2 to produce a powdercoating composition. This powder coating composition is applied to testpanels as it is described in Example 2. The coated panels are baked at Cfor 15 minutes. The coating on each panel has good adhesion and solventresistance.

EXAMPLE l0 A'monomer mixture having the following composition isprepared: itaconic anhydride 4 grams, glycidyl methacrylate 4 grams,methyl methacrylate 42 grams, methacrylamide 10 grams, butylmethacrylate 40 grams, and the initiator AIBN 4 grams. The mixture isreacted and processed as described in Example 5 to produce a groundcopolymer.

One hundred parts by weight of the ground copolymer is mixed with thefollowing materials:

Tetraethylammonium bromide 0.2 parts Ethyl benzyl(ethyleneoxy) phosphatc 0.5 parts Poly (Z-ethylhexyl acrylate) (UL-i500) 0 4 partsChromium green oxide 8 parts Titanium dioxide 10 parts Dioctyl sebacate7 parts The above mixture is processed as described in Example 2 toproduce a powder coating composition. The powder coating composition isapplied to a plurality of test panels as is described in Example 2. Thepanels are baked at a temperature of C for 20 minutes. The adhesion tothe test panels of the powder coating material is good.

There has been disclosed herein powder coating compositions which may beemployed in the painting of articles. Many modifications of thisinvention will be apparent to those skilled in the art in view of thisspecification. It is intended that all such modifications which fallwithin the scope of this invention be included within the appendedclaims.

What we claim is:

l. A powder coating composition which, free of catalyst, pigments andother ingredients, comprises a mixture .of: A. a copolymer containing(a) approximately stoichiometric' quantities of two mono-ethylenicallyunsaturated monomers, one monomer containing from about 2 percent byweight to about 12 percent by weight epoxy functional groups and theother monomer containing from about 2 percent by weight to about 8percent by weight anhydride functional groups and (bimodifying monomerscontaining no functional groups and so selected that said copolymer hasa glass transition temperature in the range of 40C to about 90C and amolecular weight (1%,) in the range of from about 3,000 to about 10,000;and B. a flow control agent forming at least from about 0.05 percent toabout 4.0 percent by weight of the mixture, said flow control agentbeing a polymer having a molecular weight ($1,) of at least 1,000, saidflow control agent being a polymer or a copolymer selected from thegroup consisting of acrylate esters, methacrylate esters andpolyethylene or polypropylene glycol esters of fluorinated fatty acids.

2. A powder coating composition which, exclusive of catalyst, pigment,plasticizer, and an antistatic agent, comprises a mixture of:

A. a copolymer containing (a) approximately stoichiometric quantities oftwo mono-ethylenically unsaturated monomers, one monomer containing fromabout 2 percent by weight to about 12 per cent by weight of epoxyfunctional groups and the other monomer containing from about 2 percentby weight to about 8 percent by weight anhydride functional groups, and(b) ethylenically unsaturated monomers containing no functional groupsand so selected that when both types of said monomers are reacted attheir sites of unsaturation to form said copolymer, said copolymer willhave a glass transition temperature in the range of 40C to 90C and amolecular weight (M,,) in the range of 3,000 to about 10,000; and

B. a flow control agent forming from at least about 0.05 percent toabout 4.0 percent by weight of the mixture, said flow control agentbeing a polymer having a molecular weight (M,,) of at least 1,000, saidflow control agent being a polymer or copolymer selected from the groupconsisting of acrylate esters, methacrylate esters and polyethylene orpolypropylene glycol esters of fluorinated fatty acids.

3. A powder coating composition comprising a mixture of:

A. a copolymer formed from (a) approximately stoichiometric quantitiesof a monomer containing from about 2 percent to about 12 percent byweight of epoxy functional groups selected from the group consisting ofglycidyl methacrylate and glycidyl acrylate and a monomer containingfrom about 2 percent to about 8 percent by weight of anhydridefunctional groups selected from the group consisting of maleicanhydride, itaconic anhydride, citraconic anhydride, dodecenyl succinicanhy dride, dichloromaleic anhydride, and tetrahydraphthalic anhydride,said copolymer also containing (b) ethylenically unsaturated modifyingmonomers having no functional groups and so selected that said copolymerhas a glass transition temperature of from 40C to about C and amolecular weight (M,,) in the range from about 3,000 to about 10,000;

B. a flow control agent forming from at least 0.05 I

percent to about 4.0 percent by weight of the mixture, said flow controlagent being a polymer having a molecular weight (M,,) of at least 1,000,said flow control agent being a polymer or a copolymer selected from thegroup consisting of acrylate esters, methacrylate esters andpolyethylene or polypropylene glycol esters of fluorinated fatty acids;and

C. a small weight percent of a catalyst which produces a gel time forthe powder coating composition greater than 1 minute at the bakingtemperature of the composition.

4. A powder coating composition of claim 3 wherein: said modifyingmonomers are selected from the group consisting of methyl methacrylate,butyl methacrylate, ethyl acrylate, butyl acrylate, Z-ethylhexylacrylate, styrene, alpha methyl styrene, acrylonitrile, andmethacrylonitrile.

5. The powder coating composition of claim 3 wherein: a pigment isincluded which forms from about 6 percent by weight to about 35 percentby weight of the total mixture, wherein: a small weight percentage of anantistatic agent is included, and wherein: a plasticizer is includedfrom about 2 percent by weight to about 10 percent by weight'of thetotal mixture.

* i It 4:

2. A powder coating composition which, exclusive of catalyst, pigment,plasticizer, and an antistatic agent, comprises a mixture of: A. acopolymer containing (a) approximately stoichiometric quantities of twomono-ethylenically unsaturated monomers, one monomer containing fromabout 2 percent by weight to about 12 percent by weight of epoxyfunctional groups and the other monomer containing from about 2 percentby weight to about 8 percent by weight anhydride functional groups, and(b) ethylenically unsaturated monomers containing no functional groupsand so selected that when both types of said monomers are reacted attheir sites of unsaturation to form said copolymer, said copolymer willhave a glass transition temperature in the range of 40*C to 90*C and amolecular weight (Mn) in the range of 3,000 to about 10,000; and B. aflow control agent forming from at least about 0.05 percent to about 4.0percent by weight of the mixture, said flow control agent being apolymer having a molecular weight (Mn) of at least 1,000, said flowcontrol agent being a polymer or copolymer selected from the groupconsisting of acrylate esters, methacrylate esters and polyethylene orpolypropylene glycol esters of fluorinated fatty acids.
 3. A powdercoating composition comprising a mixture of: A. a copolymer formed from(a) approximately stoichiometric quantities of a monomer containing fromabout 2 percent to about 12 percent by weight of epoxy functional groupsselected from the group consisting of glycidyl methacrylate and glycidylacrylate and a monomer containing from about 2 percent to about 8percent by weight of anhydride functional groups selected from the groupconsisting of maleic anhydride, itaconic anhydride, citraconicanhydride, dodecenyl succinic anhydride, dichloromaleic anhydride, andtetrahydraphthalic anhydride, said copolymer also containing (b)ethylenically unsaturated modifying monomers having no functional groupsand so selected that said copolymer has a glass transition temperatureof from 40*C to about 90*C and a molecular weight (Mn) in the range fromabout 3,000 to about 10,000; B. a flow control agent forming from atleast 0.05 percent to about 4.0 percent by weight of the mixture, saidflow control agent being a polymer having a molecular weight (Mn) of atleast 1,000, said flow control agent being a polymer or a copolymerselected from the group consisting of acrylate esters, methacrylateesters and polyethylene or polypropylene glycol esters of fluorinatedfatty acids; and C. a small weight percent of a catalyst which producesa gel time for the powder coating composition greater than 1 minute atthe baking temperature of the composition.
 4. A powder coatingcomposition of claim 3 wherein: said modifying monomers are selectedfrom the group consisting of methyl methacrylate, butyl methacrylate,ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, styrene, alphamethyl styrene, acrylonitrile, and methacrylonitrile.
 5. The powdercoating composition of claim 3 wherein: a pigment is included whichforms from about 6 percent by weight to about 35 percent by weight ofthe total mixture, wherein: a small weight percentage of an antistaticagent is included, and wherein: a plasticizer is included from about 2percent by weight to about 10 percent by weight of the total mixture.